Abstract: Weizhou6-1 oilfield applies three-in-one technology for the development of ocean oilfield as the first one in domestic.Moreover,the application of three-in-one technology in the oilfield is more difficult than that in other oilfield in world.According to actual conditions of Weizhou6-1 oilfield,process features of three-in-one technology are systematically described,meantime,many most important elements such as three-in-one wellhead technology,surface drilling technology,main points of surface casing running in,surface cementing operation,and so on are introduced.Successful application of three-in-one technology of Weizhou6-1 is a significant breakthrough,offering some precious operation experience for such wells in future.